The article presents the results of studies on the effectiveness of herbicides use for corn cultivation. It is found that in the current weather conditions during the study period, the greatest effect in protecting corn crops against weeds has been obtained when using the herbicide Adengo, SC (0.4 l / ha) at 2-3 leaves of the crop stage. At the same time, the death of weeds has made 98.2 %, their wet weight –99.6 %, green mass kept yield - 115.6 %, and grain –90.2 %.

The article presents the results of studies to determine the biological threshold of harmfulness of annual dicotyledonous weeds in winter triticale crops. It has been determined that there is a close inverse correlation between the indicators of weed infestation (the number and weight of weeds) and winter triticale grain yield. The pattern is confirmed, the more weed plants grow in crops, the more vegetative mass they form, and in accordance with this, the negative impact on the crop increases. So, with the growth of 5 weeds in crops, the crop losses are 3,0-9,9 %; 10 pcs/m² – for .8-15,4 %; 15 pcs/m² – 9,9-16,3 %; 25 pcs/m² – 12,8-24,5 %; 50 pcs/m² - 19,2-30,6 %. The determination coefficient (R²) shows that a decrease in winter triticale yield for 82-94 % depends on the number of weeds and for 85–94 % on the weight. The biological threshold of annual dicotyledonous weeds harmfulness, at which a significant winter triticale grain yield decrease has made 26 ± 2 weeds per m² depending on weather conditions (in dry years – 26 pcs/m², in wet years – 28 pcs/m²).

In the article the results of studying the herbicide Adengo, SC (thiencarbazon-methyl, 90 g/l + isoxaflutol, 225 g/l + cyprosulphamide /antidote/, 150 g/l) and its tank mixtures on crops weed infestation by application at different corn stages are stated. In 2018 the efficiency of pre-emergent herbicide Adengo, SC application at the rate of 0,4 l/ha has made 98,8 %, at corn seedlings (awls) stage – 99,2 %; at 4-5 leaves of the crop -94,6 %, accordingly. As a result of weed infestation decrease the preserved corn seed yield has made 79,5-92,0 cwt/ha. The tank mixture of Adengo, SC (0,3 l/ha) + Ballerina, ES (0,2 l/ha) has decreased corn crops weed infestation for 99,0 %, corn yield has made 113,3 cwt/ha.

The article presents the results of studying the use of herbicides Balancer, OD (rimsulfuron, 62.5 g/l); Horse, WDG (nikosulfuron, 750 g/kg); Getman, WDG (nikosulfuron, 500 g/kg + rimsulfuron, 250 g/kg) on corn crops weed infestation by application at 2-6 leaves of the crop stage. The effectiveness of the studied herbicides against barnyard grass (Echinochloa crusgalli (L.) Beauv.) has been at the level of 93-99 %. The vegetative weight of couch grass (Elytrgia repens (L.) Nevski) stalks has decreased for 96-100 % when applying the herbicides Balancer, OD; Horse, WDG; Getman, WDG at the highest rate. From annual dicotyledonous weeds Balancer, OD; Horse, WDG and Hetman, WDG effectively suppressed chamomile (Tripleurospermum inodorum Sch.-Bip.), chickweed (Stellaria media (L) Vill.) and bedstraw (Galium aparine L.).

The article presents the results of studies on the thresholds of harmfulness determination for annual dicotyledonous weed plants in blue lupine crops of different maturity varieties. Thresholds of weed plants harmfulness in blue lupine early-ripening variety Pershatsvet have made up to 5-11 pcs/m², mid-ripening variety Mirtan – 9-10 pcs/m². We are of the opinion that with such contamination, herbicides application is necessary.

The results of biological efficiency of the herbicide Roundup flex, AS (glyphosate 480 g/l) application to control annual and perennial weed plants during autumn period on grain crops stubble and also as a desiccant in winter wheat for grain drying on roots and destroying weed vegetation are presented.

In the article a problem of spring grain crops weed infestation for the period of 2017-2018, in particular naked and glumiferous oats and also spring wheat by weed plants of the family Poaceae is shown. Grass weedy coenosis of the experimental plot for the given crops, on the average, is represented by 3 species : barnyard grass (Еchinochloa crus-galli (L.) Beauv.) – 85,0 % from total number of annual weed plants, coach grass (Elytrígia repens (L.)) – 10,0 %, rough – stalked meadow grass (Poa annua (L.) – 5,0 %.
It is determined that the critical grass weed vegetation harmfulness period in spring wheat has made 29-30 days of the combined crop vegetation and weed plants (tillering stage - beginning of leaf-tube formation); naked oats - 27-36 (4 leaves – leaf-tube formation stage); glumiferous oats -32-34 days (tillering).

For the first time in the conditions of the Brest region, the effectiveness of the use of the herbicide Gambit, SC (promethrin, 500 g/l) in the first year perforated leaf sylphia crops has been studied. The preparation has been applied before crop germination at the rate of 2-4 l/ha. It is determined that the use of this herbicide on moistered soil is highly effective (reducing the weed mass up to 90 %). The preparation inhibits the emergence of crop seedlings for 5-10 days, however, by the end of the vegetative period, the crop growth and development rates in variants with the use of herbicide are significantly higher. According to the results of the experiment the State registration of the herbicide «Gambit» for perforated leaf sylphia has been done.

In the article the results of herbicide NERTA, SC (diflufenican, 100 ml/l+isoproturon, 500 ml/l) biological efficiency study in winter grain crops by autumn and spring application under conditions of the Republic of Belarus are presented. Based on the results of done researches it is determined that the herbicide used in winter grain crops in autumn before crops emergence and also by vegetation (at 1-3 leaves of the crops and tillering in autumn or in spring) at the rates 0,75-1,0 l/ ha, is effective against annual dicotyledonous and grass weeds.

It is shown that the assortment of herbicides permitted in winter grain crops makes 119, winter triticale – 99, winter rye – 60 preparations, what creates quite a lot of problems during the tender for the purchase. By danger for warm-blooded the second class of danger herbicides have become safer (high toxic) have made 8,4-10,1%, the third class (medium toxic) -77,8-78,3%, the forth ( little toxic) 11,7-13,4%. Taking into account the fact that the safety measures of the third and forth class of danger herbicides for bees are quite close, one can approve a high degree of safety of the herbicide assortment for bees at the disposal as for winter grain crops a share of the 3-rd class of danger herbicides is increased (little dangerous) – 53,3-61,3% and a share of the little class of danger is decreased (practically non-dangerous for bees) – 38,7-46,7%.

As a result of carried out researches the biological threshold of weeds harmfulness at mixed type of weed infestation is determined (50 % - monocotyledonous and 50 % - dicotyledonous) in corn crops, cultivated for corn, which has made 3,5 pcs/m² – in 2016 , 1,6 – in 2016 and 3,4 pcs/m² - in 2018, on the average, for three years of researches - 2,8 pcs/m².

As a result of done in 2016-2018 route field under corn surveys, it has been determined that before taking protective measures, corn weed infestation has made 277.4-331.9 pcs/m². From annual weeds dominate chicken millet (Echinochloa crus-galli), fat hen (Chenopodium album), field violet (Viola arvensis), etc.; from perennial ones – couch grass (Elytrigia repens) and sow thistle species (Sonchus spp.).
It is determined that herbicide tank mixtures by application at 3-5 leaves of the crop suppress effectively annual and perennial dicotyledonous and grass weeds, including such hardly eradicated weeds as couch grass (Elytrigia repens), sow thistle (Sonchus arvensis), white campion (Melandrium album) and creeping thistle (Cirsium arvense). Their biological effectiveness has made 92.0-99.0 %.

At Heracleum sosnowskyi height 20-30 cm the tank mixtures application is effective enough: Terrsan, WDG + Volnik Super, AS have made a decrease of Heracleum sosnowskyi for 85,7–97,6 %, weight – for 97,6–99,5 %; Volnik Super, AS + Magnum, WDG – 60,7-80,4% and 92,3–95,8 %, accordingly. The tank mixtures application is effective at overgrown plants, height 80-150 cm. Terrsan, WDG + Volnik Super, AS have decreased Heracleum sosnowskyi number for 60,0–76,7 %, weight – for 77,3–88,9 %; Tornado 500, AS + Magnum, WDG – 78,9–83,3 % and 93,1–94,0 %, accordingly.

It is determined that Heracleum sosnowskyi’s stems with roots digging out decreases its density for 92,1–100 %, many times mowing down – for 8,2–12,1 %, however, these methods demand high labor expenses: digging out of one Heracleum sosnowskyi plant – 0,133 rbl./plant, 4–5 times mowing down per season – 1956–2445 rbl./hа. Herbicides application is economically more profitable: the expenses for them make from 415 to 693 rbl./hа.

A period of safe weed plants growing in marketable common valerian plantings (Valeriana officinalis L.) should not increase 20 days. The competition during 30-40 days leads to raw material yield deficiency for 29,1-51,2 % (rhizomes with roots). The maximum losses at competition during 50-60 days can make 76,1-84,4.

The application of clopyralid-based herbicides in motherwort (Leonurus quinquelobatus Gilib.) perennial plantings allows to clean fully the plantings of Matricaria inodora, Cirsium arvense and Sonchus arvensis, the graminicides application – Elytrigia repens. At low weed plants density motherwort dry grass yield after herbicides application more often is at the experimental error level, at high weed plants density the grass yield increase for 12-32 % has been observed.

The results of the antagonistic activity studies of Trichoderma fungi in relation to the dominant root-habitat plant pathogens isolated on the territory of Belarus and Azerbaijan are presented. It has been determined that for the most of the studied antagonist strains a mixed type of antagonistic action with the pronounced fungistatic trophic, antibiotic, and territorial antagonism is characteristic. The strains of Trichoderma sp. IZR F-183 and Trichoderma sp. IZR F-186 with a high rate of inhibiting the pathogens growth and a multifunctional antagonistic mechanism of activity have been selected.

One of the most common and noxious sugar beet diseases is cercosporosis (agent Cercospora beticola Sacc.). With a severe damage, root crops yield and sugar content are significantly reduced, physiological processes are disturbed. It is found that with the intensity of severity increase, the chlorophyll a, chlorophyll b content, the sum of chlorophylls and the sum of carotenoids is decreased. A decrease in the intensity of photosynthesis is also noted as the intensity of leaf damage by the disease increase. A significant modulation of the antioxidant system has been revealed, having been manifested itself in a change of low molecular weight antioxidants levels - phenolic compounds - and antiradical activity in leaf tissue.

The results of biennial researches on studying the biological and economic efficiency of fungicides: Brisk, EC (0,3 and 0,35 l/ha), Soligor EC (0,6 and 0,8 l/ha), Tilt Turbo, EC (0,8 and 1,0 l/ha) and Zamir Top, EC (0,8 and 1,0 l/ha) for winter rye leaf apparatus protection against the diseases are presented. It is shown that the application of the indicated fungicides significantly decreases rhynchosporiosis development with the biological efficiency from 58,8 to 91,3 % and promotes keeping grain yield up to 7,5 cwt/ha.

The results of phytopathological situation monitoring in fodder beans crops are presented. It is determined that plants are affected everywhere by fusarium wilt, alternaria blight, blackish and chocolate spots and rust. The use of fungicides Chorus, WDG and Elatus Ria, SC has contributed to reducing the development of these diseases in crops, allowing maintaining 9,0–12,4 c/ha seed.

Spring triticale severity by fusarium root rot and fusarium head blight causes an essential yield decrease. Fusarium root rot is manifested in ear length decrease for 4,9-24,5 %, number of grains in the ear – for 4,3-9,7 %. Ear damage by fusariosis decreases grain weight from ear for 5,6-33,3 % and 1000 grain weight for 6,5-28,5 %.

The last years (2013 and 2017) in the Republic of Belarus spring barley infection by dwarf leaf rust is noticed. In the article the literary data on incidence and economic importance of the disease and the agent’s biology are combined. The results of dwarf leaf rust severity researches of spring barley crops (the disease severity by years have fluctuated depending on the variety from 0,1 to 7,1 %). A high biological fungicides efficiency in the disease severity restriction is determined.

The results of four-year (2014-2017) studies on the identification of the critical stage for corn cobs infection by fusarium wilt agents are presented. A vulnerable stage has been determined for the infection by fungi of the genus Fusarium - st. 71-73. The harmfulness of cobs fusarium wilt has been determined, which is manifested in cob mass and weight of 1000 grains decrease. Grain yield losses by the fungus Fusarium verticillioides have made 2,5-8,1 %, Fusarium graminearum - 2.9-10.3 %.

The evaluation results of Belarusian selection potato hybrids resistance to potato wart disease and golden potato nematode are presented. It is determined that from total inspected variety samples 83,6 % have not been susceptible to potato wart agent Synchytrium endobioticum (Schilb.) Perc. and 63,1 % to golden potato nematode Globodera rostochiensis (Woll.) Behrens.

The article presents the results of studies on the influence of environmental factors on spread and development of cucumber plant diseases in greenhouses. As a result of the phytopathological monitoring of cucumber plant diseases (Cucumis sativus L.) in the greenhouse agrocenoses of Ukraine in 2015-2018 it has been determined that in the structure of cucumber diseases root rot takes 39.1 %, alternaria blight of seedlings - 20.7 % and cladosporiosis - 15.2 %.

In 2012–2018 the species composition of Cereal leaf beetles in agrocenoses of winter cereal crops has been clarified, the ecological and biological features of dominant species have been determined, seasonal dynamics of their abundance and harmfulness has been revealed. An assessment of the biological and economic effectiveness of insecticides from various chemical classes is given.
It is determined that from the group of winter grain crops the pest is the most numerous and harmful in triticale crops. All studied varieties of winter crops of domestic and foreign selection are populated and damaged by the phytophage larvae. The biological effectiveness of insecticides from the group of synthetic pyrethroids and neonicotinoids has made up to 76,8-100 %, what has allowed to save 0,6-10,6 % of the grain yield of winter grain crops.

In the article the results of studying the efficiency of the insecticide Espero, SC are presented. It is determined that on the 3-rd day after carrying out the first treatment rape blossom beetle number has decreased for 78,3-89,1 %, after the second one – 81,3-92,2 %. The biological efficiency on the 5-th day after the repeated application of the preparation in the variants with the maximum rates of application has made 77,8-80,6 %, minimum – 69,5 %, on the 10-th day – from–56,4 to 66,7 % in all the experimental variants. A degree of plants damage by cabbage moth in the variant with the insecticide Espero, SC treatment at the rate of 0,1 l/ha has decreased for 69,5 %, 0,15 – for 77,3 and 0,2 l/ha – for 75,9 % at plants severity in the control 24,7 %.

In the article the results of pheromone monitoring of the European corn borer (Ostrinia nubilalis Hbn.) in 2014–2015 in the formed focuses with a high pest number in corn crops cultivated in different agroclimatic zones of Belarus are presented. Low attractiveness of pheromone compositions «Z», «Е» and «ZЕ» mixture for Belorussian corn borer populations is determined. The factors influencing males catching by synthesized pheromones of the European corn borer females are discussed.

A review of dendrophilous leaf mining flies (Agromyzidae), feeding on ornamental plants in Belarus has been presented, lists of damaged plants and brief descriptions of mines are given. The indexes of physiological injuriousness, ecologically conditioned and general harmfulness for 13 species of mining flies, damaging ornamental woody plants in conditions of green plantings, are calculated. On the basis of the data obtained, the miners have been divided into groups according to the level of their harmfulness in decorative greenery of Belarus.

Based on the results of perennial surveys of trees and shrubs of ornamental green stands an assessment of the physiological harmlessness, environmental (environmentally determined) and total harmfulness of 14 invasive species of open-living hemipteroid insects in the conditions of 5 areas of woody plants introduction in Belarus is provided. Estimated indicator of physiological harmlessness progressively increased from the Northern, North-Central regions to the South-Central, West and South, which is associated with an increase in the vegetation period of phytophagous fodder plants and the duration period of damage caused by pests. Statistically significant differences in the values of the indicator of environmental and total harmfulness have been found between South/West, South/South-Central, South/North-Central, South/North, West/South-Central, West/North-Central, West/North, South-Central/North-Central and Northern/South-Central regions of introduction. In general, the levels of ecological and total harmfulness of invasive species of openlived hemipteroid insects are higher in the conditions of the Southern and Western than in the North-Central and Northern regions of woody plants introduction.

The results of researches of Helicoverpa armigera Hbn. pests harmfulness on corn hybrids of different maturation stages conducted in 2017-2018 are presented in the article. Susceptibility of the most corn hybrids to the pest has been determined. It is determined that cotton bollworm population on corn plants has been unequal (12,5–77,5 %) depending on maturity of the given hybrids group. Concerning damage of corn cobs by Cotton bollworm larvae - the difference between hybrids of different term of maturity is a significant. The most damaged corn cobs have been middle ripening hybrids (Demetra and Adgamka), and the least damaged - on middle-early ripening hybrids (Svitjaz, Vita and 3472 (Monsanto)).

The results of the economic expediency thresholds of insecticides application for pre-sowing seed treatment and during vegetation for corn protection against wireworms and the European corn borer are presented in the article.
It is determined that for corn protection against wireworms the pre-sowing corn seed treatment by the insecticidal action preparations for seed growing is expedient at the pest number before sowing 11,0-20,0 indiv./m2 , for green mass – 17,0-20,0 indiv./m2. At tasseling with corn cultivation for grain the insecticides application depending on their price is expedient at the European corn borer number 4,0-8,0 egg layings/100 plants, for green mass – 5,0-12,0 egg layings/100 plants.

The article presents the data on study the fungicides persistence fluopyram, pyrimethalin and diphenoconazole in apple fruits. The statistical probabilities of finding the residues in apples are determined.

The article describes an approach to the determination of isoxaflutole in corn green mass. A method has been developed for the determination of isoxaflutole residues which is based on alkaline hydrolysis of active substance in RPA 202248 metabolite and subsequent use by high-performance liquid chromatography using a diode-matrix detector.

A method has been developed for the determination of the the active ingredient fluorochloridone microquantities in potato tubers. The method is based on the extraction of the determined compound with an acetone-hexane mixture, purification of extracts in a system of immiscible solvents, additional purification of samples by column chromatography, followed by determination by gas-liquid chromatography (GLC) with an electron capture detector. The method allows you to set the value of the lower limit of quantification and the level of extraction sufficient for detecting the residues in potato tubers below the determined maximum permissible level (MPL) of the pesticide content in the crop.

The method of c-metolachlor herbicide microqualities determination in sugar beet, potato, soil and water is developed. The method is based on c-metolachlor extraction from water by chloroform , from plant samples and soil by water – acetone mixture, dry residues bromating with the subsequent determination by gas-liquid chromatography. Limit of discovery (mg/kg): water – 0,001; soil – 0,01; sugar beet – 0,005-0,01; potato – 0,005.

The article presents data on the behavior study of the active substances tebuconazole and fluopyram of the fungicide Luna Expiriens, SC in raspberries and apples, in carrots and cucumbers. It is found that the residues of tebuconazole and fluopyram have been found in raspberries and carrot roots on the 20th day after treatment and on the 30th day after treatment in apples in quantities less than the maximum allowable level (hereinafter referred to as MDL).

The article presents the results of studies on the effect of combined preparations – Prestige, SC (imidacloprid, 140 g/l + pencicuron, 150 g/l; 1.0 l/t), Emesto Quantum, SC (penflufen, 66.5 g/l + clothianidin, 207 g/l; 0.35 l/t), Сelest Top, SC (thiamethoxam, 262.5 g/l + diphenoconazole, 25 g/l + fludioxonyl, 25 g/l; 0.4 l/t), Vibrance Maxx, FS (thiamethoxam, 262.5 g/l + sedaxane, 25 g/l + fludioxonyl, 25 g/l; 0.5 l/t), applied by the method of pre-planting tubers treatment for the formation of biometric indicators of Breeze and Scarb potato varieties. It is determined that some preparations have got a negative effect on the growth and development of plants: on Scarb variety the germination has been reliably decreased (Prestige,SC), stems number (Сelest Top, SC) and plant height (Prestige, SC; Vibrance Maxx, FS; Сelest Top, SC), on Breeze variety – stems number and plant height (Сelest Top, SC). However, there has been no reliable decrease in productivity. The absence of a phytotoxic effect on potato plants has been identified with the use of Emesto Quantum, SC. The necessity of strict observance of technological regulations when using insecticidal-fungicidal preparations in the systems of potato protection against noxious organisms in agricultural enterprises of the republic is indicated.